The development of electroredox equipment, scaled up from laboratory apparatus to industrial application for the reprocessing of spent nuclear fuel, which is carried out worldwide by the Purex process, is presented. The design of the different electroredox equipment is described and operational results achieved in experimental facilities in laboratory and bench-scale equipment, as well as in an industrial reprocessing plant (Wiederaufarbeitungsanlage Karlsruhe, WAK), are described. The separation efficiency of plutonium from uranium is essentially increased by integration of electroreduction of tetravalent plutonium into liquid/liquid extractors. Electrooxidation of trivalent plutonium and of hydrazine lead to compact apparatus and simple and reliable process steps avoiding radioactive contaminated waste. The experimental work was connected with the development of a mathematical model (VISCO) finally allowing the simulation of the whole separation process. This enabled a drastic simplification of the whole Purex process demonstrated in the miniature reprocessing plant (MILLI) in the late 1980s.